1. Field of the Invention
This invention relates to a safety enhancement device combination for electrical apparatus or appliances of the type which has a thermal cut-off device in the apparatus, and a non-replaceable fuse in the cordset plug of the apparatus or appliance.
2. Description of the Prior Art
Air moving apparatus, appliances with a motor, or with electric heating elements are potentially subject to electrical problems due to accident, misuse, excessive moisture and/or heat, which can cause the wiring in a motor, or the cordset or other wires to short. Motors in appliances often incorporate a thermal cut-off device which reacts to heat increase to shut off the motor. Thermal devices are generally slow acting and designed to sense and react to a gradual heat increase. The heat increase can be caused by a variety of factors such as a slow acting shorting in the motor windings, or bearing failures which would cause air flow across the windings to cease, which causes the windings to heat up.
Thermal devices are most effective at sensing localized heating, such that if a failure occurs at a location remote from the thermal device, the thermal device may not sense the condition, quickly enough to shut the motor down prior to failure.
Rapidly acting remote failures may delay the thermal device operation and damage to the device may result.
A fuse will react to rapid failure conditions, and current increase over its capacity, and will protect components upstream from the motor, such as the cordset. A fuse will also react to foreseeable shorts internal to the switch, lead wires, and motor windings.
A fuse, to be effective, must be non-replaceable in order to insure that the user does not defeat the purpose of the fuse, which is to enhance safety of the thermal fuse thus preventing damage to components or the apparatus or appliance. The combination of these two devices in an electrical apparatus or appliance will enhance the safety of the apparatus or appliance as well as act to protect its components.
This invention relates to a safety enhancement device combination for an electrical apparatus or appliance which includes a thermal cut-off device in the apparatus and a non-replaceable fuse in the cordset plug.
The principal object of the invention is to provide an enhanced safety device combination to protect electrical apparatus or appliances from damage due to excessive heat or shorts.
A further object of the invention is to provide an enhanced safety device combination as aforesaid that is fast and positive in operation.
A further object of the invention is to provide an enhanced safety device combination as aforesaid that is useful with a wide variety of electrical apparatus or appliances, wherein the appliances may have inductive, capacitive or tungsten type loads. The fuse portion of the enhanced safety device can be matched to the load type by current value and trip characteristics. Inductive loads where in rush currents start low may use a fast trip fuse. Tungsten and capacitive loads with higher in rush currents may be designed with a slow blow.
A further object of the invention is to provide a reliably manufacturable assembly. The high injection pressures involved with molding plastic around the plug assembly can move the component parts, and potentially create an intermittent or open connection. Component parts are encapsulated with a cap and cover preventing the invasion of plastic during the molding operation.
A further object of the invention is to provide an enhanced safety device which is no larger than devices typically found in the marketplace, although containing an additional fuse. This is achieved by locating the device components in slots and cavities integral to the cap.
A further object of the invention is to provide an enhanced safety device combination as aforesaid that is reliable and inexpensive to construct.
A further object of the invention is to provide an enhanced safety device combination as aforesaid that enhances the safety of the apparatus or appliance. Other objects and advantageous features of the invention will be apparent from the description and claims.